Electrochemical Study on the Emulsion Stabilized with Soybean Phospholipid

Abstract

Effect of pH of water phase on creaming stability and electric conductivity of the kerosine-water (1:1) O/W emulsions stabilized with soybean phospholipids, that is, commercial soybean lecithin (CSL), ethanol-extracted lecithin from CSL (EL), phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI), were investigated. Higher stability waS generally obtained in the middle region of pH. The effect of the combinations of the phospholipids on the emulsion stability was cumulative. Electric conductivities of the emulsion phases of all samples decreased with aging time. The conductivity of the CSL emulsion was much higher than those of other phospholipid emulsions. The increasing order of the emulsion conductivities (PI>PE>PC) was parallel with that of the emulsion stability, and the conductivity of the PC emulsion showing worst stability was very low and decreased rapidly during aging. Very high conductivity was observed for the emulsions with two and three phospholipid mixtures and tevalue of the sample containing greater amount of PI was very high. These results suggest that the interfacial film structure and the charge strength of emulsion droplets may depend on the electrical charge of phospholipid resulting in the different stabilities of individual emulsions.